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Lattice dynamics of chalcopyrite semiconductors LiAlTe 2 , LiGaTe 2 and LiInTe 2
Author(s) -
Kosobutsky A. V.,
Basalaev Yu. M.,
Poplavnoi A. S.
Publication year - 2009
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200844283
Subject(s) - phonon , tetragonal crystal system , raman spectroscopy , chemistry , condensed matter physics , ion , molecular vibration , semiconductor , crystallography , physics , crystal structure , optics , quantum mechanics , organic chemistry
Within density functional perturbation theory using norm‐conserving pseudopotentials and a plane‐wave basis set calculations of phonon dispersion relations and densities of states of LiAlTe 2 , LiGaTe 2 and LiInTe 2 compounds being crystallized into the tetragonal chalcopyrite structure have been performed. Theoretical values of phonon mode frequencies in LiGaTe 2 and LiInTe 2 are in good agreement with the experimental data available for these crystals obtained by the methods of Raman and infrared spectroscopies. The similarity of the physical and chemical properties of the crystals concerned manifests itself in the similarity of their phonon spectra that are especially close to each other in low‐ and high‐frequency ranges. Phonon modes of the upper phonon band are predominantly caused by the lithium sublattice vibrations and have an upper bound of 350–370 cm –1 . In a mid‐frequency range a significant downshift of the vibrational frequencies is observed on going from LiAlTe 2 to LiGaTe 2 and LiInTe 2 that is a consequence of the third group cation mass reduction. From calculated electron density maps it follows that Li‐containing chalcopyrites are characterized by a less pronounced bond between the first group cation and anion as compared with the Cu‐ and Ag‐based analogs due to the absence of pd‐hybridization. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)